The underlying goal of this project is to determine the mechanisms by which polypeptide growth factors control the proliferation of normal human cells and how these growth factors may be involved in the development of a malignant tumor. One growth factor that may be involved in this process is a polypeptide growth factor known as heparin-binding growth factor, type-2, or basic fibroblast growth factor (HBGF-2/bFGF). This growth factor can control the rate of proliferation of normal human cells in vitro under highly defined conditions. These cells include cells of stromal (fibroblastic) and epithelial origin. HBGF-2/bFGF may contribute to the development of a solid tumor mass by stimulating the proliferation of the tumor cells themselves (vis paracrine, autocrine or intracrine mechanisms), and/or by stimulating the proliferation and invasion of stromal elements including fibroblasts and endothelial cells. The specific aims of this project will help elucidate possible roles of this growth factor in the proliferation of normal cells and examine the production of the growth factor by human cells of normal and neoplastic origin grown in vitro. A mouse cell line that is missing the receptor for the growth factor will be isolated. This cell line will be of value in future structure-function studies on the molecular mechanisms by which the ligand-receptor interaction can stimulate the proliferation of mammalian cells.